BIOL 2420 Lecture Notes - Lecture 20: Cooperative Binding, Cardiac Output, Conformational Change
13 Mar 2017
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I) oxyhemoglobin (hbo2) - r or relaxed state. Ii) deoxyhemoglobin (dhb) - t or tense state. R < > t transition regulated by the formation/breakage of salt bridges (weak ionic bonds) between the adjacent global subunits. Cause structural changes of the protein chains that alter the shape of the heme groups, thereby increasing/decreasing they af nity for o2. The r < > t transition can also be in uenced by the binding of other ligands (termed allosteric effectors) to the hb protein. Being a multi-subunit protein, hb exhibits both cooperative oxygen binding and allosteric modulation of o2 af nity. The four subunits of hb are connected in such a way that a conformational change in one subunit is simultaneously conferred to the other three subunits. Proteins are able to communicate between one another. Hence, oxygen binding at one site in the hb tetramer increases the oxygen binding af nity at the other sides (and vice versa)
